This invention relates generally to electronic circuitry and more particularly to absolute value circuitry.
As is known in the art, it is sometimes desirable to provide an electronic device which produces a signal proportional to the absolute value of an input signal. In known circuits of such type, operational amplifiers are included and esistor biasing network. A switching device selectively couples to the input of the operational amplifier either the input signal or an inverted version of the input signal depending on the polarity of the input signal. With such arrangements, however, the input biasing resistors cause errors in the operation of the absolute value circuit because of biasing currents passing through such resistors. Further, in such known circuits, the resistors in the resistor network which are coupled between the input signal and the input of the operational amplifier are not the same resistors as those used to couple an inverted version of the input signal to the input of the operational amplifier. Thus, since different resistors are used in the coupling processes, adjustability of the gain of the circuit using such resistors is relatively difficult to control particularly when it is desired that the same gain be provided to the input signal regardless of its polarity.